Conventionally, a gas barrier plastic film which uses a plastic film as a substrate and has an inorganic layer of silicon oxide, aluminum oxide, magnesium oxide, or the like formed on the surface thereof is widely used for wrapping of articles which require blocking of various gases such as water vapor and oxygen, for example, for wrapping to avoid deterioration of foods, industrial goods, drugs, and the like. With regard to the gas barrier plastic film, in addition to the wrapping use, in recent years, new uses have been receiving attention, which include a vacuum insulating material and a transparent conductive sheet to be used for a liquid crystal display device, a solar cell, an electromagnetic wave shield, a touch panel, a substrate for EL, a color filter, and the like.
With regard to the gas barrier plastic film formed with the inorganic layer, various improvement methods have been studied with an aim to avoid deterioration of the gas barrier property or to further enhance the gas barrier property. For example, disclosed are: a method in which a film material excellent in the gas barrier property is obtained by using a polyurethane-based resin having specific concentrations of a urethane group and a urea group (see, PTL 1); and a method in which an anchor coat layer comprising a urethane resin is formed at least one surface of a film to obtain a film for a vapor deposition (see, PTL 2).
Though the gas barrier property can be improved to some extent in these methods, film, and the like, however, the gas barrier property is still insufficient under a severe treatment condition represented by, for example, a treatment with a pressurized hot water; and therefore, the improvement thereof has been wanted.